PHOTOELECTROCATALYTIC HYDROGEN-PRODUCTION FROM WATER ON TRANSPARENT THIN-FILM TITANIA OF DIFFERENT CRYSTAL-STRUCTURES AND QUANTUM EFFICIENCY CHARACTERISTICS

Quantum efficiency of transparent thin film titania photocatalysts und er constant photon irradiation during room-temperature water decomposi tion reaction without external bias potential was measured for the fir st time as the wavelength was scanned between 250 and 1200 nm. It decr eased as the crystal structure of titania was systematically varied fr om anatase to mixtures of anatase and rutile and then to rutile. The s ame trend was observed for photocurrents measured under external bias potential. These results indicate structure sensitivity of the reactio n and intrinsic advantage of anatase over rutile. The anatase sample t ested in a single unit photoelectrocatalysis (SUPEC) cell produces hyd rogen at the rates of 0.42 1 h(-1) m(-2) without bias under sunlight a nd 26 1 h(-1) m(-2) with bias under 500 W mercury lamp where the area is the cross-section of light irradiation. Structural analyses of the photocatalysts include atomic force microscopy, laser Raman spectrosco py and X-ray diffraction.